230 research outputs found
Optical phase cloaking of 700-nm light waves in the far field by a three-dimensional carpet cloak
Transformation optics is a design tool that connects geometry of space and
propagation of light. Invisibility cloaking is a corresponding benchmark
example. Recent experiments at optical frequencies have demonstrated cloaking
for the light amplitude ("ray cloaking"). In this Letter, we demonstrate
far-field cloaking of the light phase ("wave cloaking") by interferometric
microscope-imaging experiments on the previously introduced three-dimensional
carpet cloak at 700-nm wavelength and for arbitrary polarization of light
Three-dimensional direct laser writing inspired by stimulated-emission-depletion microscopy
Three-dimensional direct laser writing has become a well established,
versatile, widespread, and even readily commercially available "workhorse" of
nano- and micro-technology. However, its lateral and axial spatial resolution
is inherently governed by Abbe's diffraction limitation - analogous to optical
microscopy. In microscopy, stimulated-emission-depletion approaches have lately
circumvented Abbe's barrier and lateral resolutions down to 5.6 nm using
visible light have been achieved. In this paper, after very briefly reviewing
our previous efforts with respect to translating this success in optical
microscopy to optical lithography, we present our latest results regarding
resolution improvement in the lateral as well as in the much more relevant
axial direction. The structures presented in this paper set a new
resolution-benchmark for next-generation direct-laser-writing optical
lithography. In particular, we break the lateral and the axial Abbe criterion
for the first time
08351 Abstracts Collection -- Evolutionary Test Generation
From September 24th to September 29th 2008 the Dagstuhl Seminar
08351 ``Evolutionary Test Generation \u27\u27 was held
in Schloss Dagstuhl~--~Leibniz Center for Informatics.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
CeCar: A platform for research, development and education on autonomous and cooperative driving
International audienceIn this paper, we introduce CeCar as an affordable model-car based platform supporting research, development and education in the field of autonomous and cooperative driving. We present the application-oriented use cases and key platform requirements , and explain the logical and technical architecture of the CeCar platform, alongside with details on the underlying mod-ularity concept. Subsequently, we introduce CeCar application scenarios for the areas research, development and education, and provide relevant application examples. Further, we discuss the CeCar platform concept in comparison with other model-car based education and research platforms, and outline planned future work on the CeCar platform
Evolutionary testing supported by slicing and transformation
Evolutionary testing is a search based approach to the automated generation of systematic test data, in which the search is guided by the test data adequacy criterion. Two problems for evolutionary testing are the large size of the search space and structural impediments in the implementation of the program which inhibit the formulation of a suitable fitness function to guide the search. In this paper we claim that slicing can be used to narrow the search space and transformation can be applied to the problem of structural impediments. The paper presents examples of how these two techniques have been successfully employed to make evolutionary testing both more efficient and more effective
A post-placement side-effect removal algorithm
Side-effects are widely believed to impede program comprehension and have a detrimental effect upon software maintenance. This paper introduces an algorithm for side-effect removal which splits the side-effects into their pure expression meaning and their state-changing meaning. Symbolic execution is used to determine the expression meaning, while transformation is used to place the state-changing part in a suitable location in a transformed version of the program. This creates a program which is semantically equivalent to the original but guaranteed to be free from side-effects. The paper also reports the results of an empirical study which demonstrates that the application of the algorithm causes a significant improvement in program comprehension
A high-precision wound healing assay based on photosensitized culture substrates
Quantitative assessment of cell migration in vitro is often required in fundamental and applied
research from different biomedical areas including wound repair, tumor metastasis or developmental
biology. A collection of assays has been established throughout the years like the most widely used
scratch assay or the so-called barrier assay. It is the principle of these assays to introduce a lesion into
an otherwise confluent monolayer in order to study the migration of cells from the periphery into this
artificial wound and determine the migration rate from the time necessary for wound closure. A novel
assay makes use of photosensitizers doped into a polystyrene matrix. A thin layer of this composite
material is coated on the bottom of regular cell culture ware showing perfect biocompatibility. When
adherent cells are grown on this coating, resonant excitation of the photosensitizer induces a very
local generation of 1O2, which kills the cells residing at the site of illumination. Cells outside the site
of illumination are not harmed. When excitation of the photosensitizer is conducted by microscopic
illumination, high-precision wounding in any size and geometry is available even in microfluidic
channels. Besides proof-of-concept experiments, this study gives further insight into the mechanism
of photosensitizer-mediated cell wounding
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